Donald Duck and his nephews manage to sink Uncle Scrooge's yacht (m = 3527 kg), which is made of steel (ρ = 7850 kg/m^3). In typical comic-book fashion, they decide to raise the yacht (which is now on the bottom of a lake) by filling it with ping-pong balls. A ping-pong ball has a mass of 2.70 g and a volume of 3.35·10-5 m^3.

a) What is the buoyant force on one ping-pong ball in water?
b) How many balls are required to float the ship?